The overall goal of this project is an understanding of the relationship between membrane architecture and function in phostosynthetic membranes. A major goal of the project is to develop the cyanobacterium Anacystis nidulans R2 into a system to allow the study of photosynthetic genetics. This strain is transformable and possesses a small (5.3 x 10 to the 6th power dalton) plasmid. The plasmid has been marked by adding a transposable gene from bacteria that codes for ampicillin resistance. In previous years, we have developed techniques for the isolation of temperature-sensitive, photosynthetic mutants in a related cyanobacterial strain. We now plan to isolate such mutants in the A. nidulans strain in preparation for cloning experiments. We are greatly interested in seeing how changes in function affect structure and visa versa. Our characterization of mutants includes physical parameters such as electron transport and fluorescence as well as structural parameters such as protein composition and architecture. We are labeling membranes with various probes to determine which proteins are on the external surface of the membrane and which are embeeded in the lipid bilayer. We will extend the analysis to the mutants to determine the type of membrane perturbations that take place.